INDIANAPOLIS (WISH) – It could take up to three months to determine what caused an underground explosion in downtown Indianapolis Wednesday, officials from Indianapolis Power and Light said. IPL has hired the company that manufactured the damaged equipment to help determine why it failed.
The explosion Wednesday afternoon right outside Circle Center Mall knocked out power to several businesses on South Meridian Street. Power was restored early Wednesday evening.
IPL said Thursday that crews cut power to the area following a series of transformer explosions in an underground vault that caused smoke and loud noises to scatter crowds. Businesses reported windows shaken by the explosions, but no one was hurt.
IPL says its internal inspection records show the vault was last inspected on February 14, 2012. Under new guidelines adopted in 2011, it was due to be inspected again within the next six months.
Aside from some road salt corrosion that was repaired, the equipment was declared fully compliant during the 2012 inspection, according to IPL spokesman Brad Riley.
Riley said the company remains uncertain what changed so dramatically to cause an explosion less than two years later.
“It’s really hard to tell,” Riley said. “There will be an ongoing investigation. We want to make sure we do a thorough investigation. We’ve actually included a third party to come in to help with that investigation, and we want to get to the root cause of what happened here. So, we don’t expect any results from that investigation for probably two to three months.”
It’s not the first time the utility has mounted such an investigation.
Records show at least 13 other underground explosions have occurred in downtown Indianapolis over the last 10 years.
But, IPL said this one was different than most others.
“Incidents that we’ve seen in the past that have involved manholes have to do with cables, or cable connection, and have not been equipment specific. This was a specific piece of equipment that failed,” Riley said.
It’s called an underground network protector, and it acts like a large-scale circuit breaker.
Late Thursday, IPL confirmed it’s hired the company that made the part, Eaton Manufacturing, to try to figure out what went wrong. Eaton’s U.S. headquarters is based in Cleveland, but the company also has offices in Indianapolis, according to online records.
It’s the same approach the utility took following a series of manhole explosions downtown.
A 2011 report commissioned by the Indiana Utility Regulatory Commission, and prepared by an independent firm, found “an immediate need to improve the process by which IPL finds, documents and remediates failures in its downtown electrical system.”
IPL issued a 46-page response to the report, which includes remediation steps it intended to take.